472 lines
12 KiB
C
472 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/pagewalk.h>
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#include <linux/highmem.h>
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#include <linux/sched.h>
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#include <linux/hugetlb.h>
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static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
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struct mm_walk *walk)
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{
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pte_t *pte;
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int err = 0;
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const struct mm_walk_ops *ops = walk->ops;
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spinlock_t *ptl;
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pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
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for (;;) {
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err = ops->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
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if (err)
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break;
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addr += PAGE_SIZE;
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if (addr == end)
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break;
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pte++;
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}
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pte_unmap_unlock(pte, ptl);
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return err;
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}
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static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
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struct mm_walk *walk)
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{
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pmd_t *pmd;
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unsigned long next;
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const struct mm_walk_ops *ops = walk->ops;
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int err = 0;
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pmd = pmd_offset(pud, addr);
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do {
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again:
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next = pmd_addr_end(addr, end);
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if (pmd_none(*pmd) || !walk->vma) {
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if (ops->pte_hole)
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err = ops->pte_hole(addr, next, walk);
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if (err)
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break;
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continue;
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}
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/*
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* This implies that each ->pmd_entry() handler
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* needs to know about pmd_trans_huge() pmds
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*/
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if (ops->pmd_entry)
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err = ops->pmd_entry(pmd, addr, next, walk);
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if (err)
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break;
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/*
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* Check this here so we only break down trans_huge
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* pages when we _need_ to
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*/
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if (!ops->pte_entry)
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continue;
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split_huge_pmd(walk->vma, pmd, addr);
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if (pmd_trans_unstable(pmd))
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goto again;
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err = walk_pte_range(pmd, addr, next, walk);
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if (err)
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break;
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} while (pmd++, addr = next, addr != end);
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return err;
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}
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static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
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struct mm_walk *walk)
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{
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pud_t *pud;
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unsigned long next;
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const struct mm_walk_ops *ops = walk->ops;
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int err = 0;
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pud = pud_offset(p4d, addr);
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do {
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again:
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next = pud_addr_end(addr, end);
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if (pud_none(*pud) || !walk->vma) {
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if (ops->pte_hole)
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err = ops->pte_hole(addr, next, walk);
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if (err)
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break;
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continue;
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}
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if (ops->pud_entry) {
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spinlock_t *ptl = pud_trans_huge_lock(pud, walk->vma);
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if (ptl) {
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err = ops->pud_entry(pud, addr, next, walk);
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spin_unlock(ptl);
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if (err)
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break;
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continue;
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}
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}
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split_huge_pud(walk->vma, pud, addr);
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if (pud_none(*pud))
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goto again;
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if (ops->pmd_entry || ops->pte_entry)
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err = walk_pmd_range(pud, addr, next, walk);
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if (err)
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break;
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} while (pud++, addr = next, addr != end);
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return err;
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}
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static int walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
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struct mm_walk *walk)
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{
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p4d_t *p4d;
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unsigned long next;
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const struct mm_walk_ops *ops = walk->ops;
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int err = 0;
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p4d = p4d_offset(pgd, addr);
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do {
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next = p4d_addr_end(addr, end);
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if (p4d_none_or_clear_bad(p4d)) {
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if (ops->pte_hole)
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err = ops->pte_hole(addr, next, walk);
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if (err)
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break;
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continue;
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}
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if (ops->pmd_entry || ops->pte_entry)
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err = walk_pud_range(p4d, addr, next, walk);
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if (err)
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break;
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} while (p4d++, addr = next, addr != end);
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return err;
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}
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static int walk_pgd_range(unsigned long addr, unsigned long end,
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struct mm_walk *walk)
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{
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pgd_t *pgd;
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unsigned long next;
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const struct mm_walk_ops *ops = walk->ops;
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int err = 0;
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pgd = pgd_offset(walk->mm, addr);
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do {
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next = pgd_addr_end(addr, end);
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if (pgd_none_or_clear_bad(pgd)) {
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if (ops->pte_hole)
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err = ops->pte_hole(addr, next, walk);
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if (err)
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break;
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continue;
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}
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if (ops->pmd_entry || ops->pte_entry)
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err = walk_p4d_range(pgd, addr, next, walk);
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if (err)
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break;
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} while (pgd++, addr = next, addr != end);
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return err;
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}
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#ifdef CONFIG_HUGETLB_PAGE
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static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
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unsigned long end)
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{
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unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h);
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return boundary < end ? boundary : end;
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}
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static int walk_hugetlb_range(unsigned long addr, unsigned long end,
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struct mm_walk *walk)
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{
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struct vm_area_struct *vma = walk->vma;
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struct hstate *h = hstate_vma(vma);
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unsigned long next;
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unsigned long hmask = huge_page_mask(h);
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unsigned long sz = huge_page_size(h);
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pte_t *pte;
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const struct mm_walk_ops *ops = walk->ops;
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int err = 0;
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do {
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next = hugetlb_entry_end(h, addr, end);
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pte = huge_pte_offset(walk->mm, addr & hmask, sz);
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if (pte)
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err = ops->hugetlb_entry(pte, hmask, addr, next, walk);
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else if (ops->pte_hole)
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err = ops->pte_hole(addr, next, walk);
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if (err)
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break;
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} while (addr = next, addr != end);
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return err;
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}
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#else /* CONFIG_HUGETLB_PAGE */
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static int walk_hugetlb_range(unsigned long addr, unsigned long end,
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struct mm_walk *walk)
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{
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return 0;
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}
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#endif /* CONFIG_HUGETLB_PAGE */
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/*
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* Decide whether we really walk over the current vma on [@start, @end)
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* or skip it via the returned value. Return 0 if we do walk over the
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* current vma, and return 1 if we skip the vma. Negative values means
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* error, where we abort the current walk.
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*/
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static int walk_page_test(unsigned long start, unsigned long end,
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struct mm_walk *walk)
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{
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struct vm_area_struct *vma = walk->vma;
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const struct mm_walk_ops *ops = walk->ops;
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if (ops->test_walk)
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return ops->test_walk(start, end, walk);
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/*
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* vma(VM_PFNMAP) doesn't have any valid struct pages behind VM_PFNMAP
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* range, so we don't walk over it as we do for normal vmas. However,
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* Some callers are interested in handling hole range and they don't
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* want to just ignore any single address range. Such users certainly
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* define their ->pte_hole() callbacks, so let's delegate them to handle
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* vma(VM_PFNMAP).
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*/
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if (vma->vm_flags & VM_PFNMAP) {
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int err = 1;
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if (ops->pte_hole)
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err = ops->pte_hole(start, end, walk);
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return err ? err : 1;
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}
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return 0;
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}
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static int __walk_page_range(unsigned long start, unsigned long end,
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struct mm_walk *walk)
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{
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int err = 0;
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struct vm_area_struct *vma = walk->vma;
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const struct mm_walk_ops *ops = walk->ops;
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if (vma && ops->pre_vma) {
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err = ops->pre_vma(start, end, walk);
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if (err)
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return err;
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}
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if (vma && is_vm_hugetlb_page(vma)) {
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if (ops->hugetlb_entry)
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err = walk_hugetlb_range(start, end, walk);
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} else
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err = walk_pgd_range(start, end, walk);
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if (vma && ops->post_vma)
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ops->post_vma(walk);
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return err;
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}
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/**
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* walk_page_range - walk page table with caller specific callbacks
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* @mm: mm_struct representing the target process of page table walk
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* @start: start address of the virtual address range
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* @end: end address of the virtual address range
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* @ops: operation to call during the walk
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* @private: private data for callbacks' usage
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*
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* Recursively walk the page table tree of the process represented by @mm
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* within the virtual address range [@start, @end). During walking, we can do
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* some caller-specific works for each entry, by setting up pmd_entry(),
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* pte_entry(), and/or hugetlb_entry(). If you don't set up for some of these
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* callbacks, the associated entries/pages are just ignored.
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* The return values of these callbacks are commonly defined like below:
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*
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* - 0 : succeeded to handle the current entry, and if you don't reach the
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* end address yet, continue to walk.
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* - >0 : succeeded to handle the current entry, and return to the caller
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* with caller specific value.
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* - <0 : failed to handle the current entry, and return to the caller
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* with error code.
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*
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* Before starting to walk page table, some callers want to check whether
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* they really want to walk over the current vma, typically by checking
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* its vm_flags. walk_page_test() and @ops->test_walk() are used for this
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* purpose.
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*
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* If operations need to be staged before and committed after a vma is walked,
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* there are two callbacks, pre_vma() and post_vma(). Note that post_vma(),
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* since it is intended to handle commit-type operations, can't return any
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* errors.
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*
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* struct mm_walk keeps current values of some common data like vma and pmd,
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* which are useful for the access from callbacks. If you want to pass some
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* caller-specific data to callbacks, @private should be helpful.
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*
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* Locking:
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* Callers of walk_page_range() and walk_page_vma() should hold @mm->mmap_sem,
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* because these function traverse vma list and/or access to vma's data.
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*/
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int walk_page_range(struct mm_struct *mm, unsigned long start,
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unsigned long end, const struct mm_walk_ops *ops,
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void *private)
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{
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int err = 0;
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unsigned long next;
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struct vm_area_struct *vma;
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struct mm_walk walk = {
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.ops = ops,
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.mm = mm,
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.private = private,
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};
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if (start >= end)
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return -EINVAL;
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if (!walk.mm)
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return -EINVAL;
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lockdep_assert_held(&walk.mm->mmap_sem);
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vma = find_vma(walk.mm, start);
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do {
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if (!vma) { /* after the last vma */
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walk.vma = NULL;
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next = end;
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} else if (start < vma->vm_start) { /* outside vma */
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walk.vma = NULL;
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next = min(end, vma->vm_start);
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} else { /* inside vma */
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walk.vma = vma;
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next = min(end, vma->vm_end);
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vma = vma->vm_next;
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err = walk_page_test(start, next, &walk);
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if (err > 0) {
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/*
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* positive return values are purely for
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* controlling the pagewalk, so should never
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* be passed to the callers.
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*/
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err = 0;
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continue;
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}
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if (err < 0)
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break;
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}
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if (walk.vma || walk.ops->pte_hole)
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err = __walk_page_range(start, next, &walk);
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if (err)
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break;
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} while (start = next, start < end);
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return err;
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}
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int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
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void *private)
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{
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struct mm_walk walk = {
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.ops = ops,
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.mm = vma->vm_mm,
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.vma = vma,
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.private = private,
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};
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int err;
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if (!walk.mm)
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return -EINVAL;
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lockdep_assert_held(&walk.mm->mmap_sem);
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err = walk_page_test(vma->vm_start, vma->vm_end, &walk);
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if (err > 0)
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return 0;
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if (err < 0)
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return err;
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return __walk_page_range(vma->vm_start, vma->vm_end, &walk);
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}
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/**
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* walk_page_mapping - walk all memory areas mapped into a struct address_space.
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* @mapping: Pointer to the struct address_space
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* @first_index: First page offset in the address_space
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* @nr: Number of incremental page offsets to cover
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* @ops: operation to call during the walk
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* @private: private data for callbacks' usage
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*
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* This function walks all memory areas mapped into a struct address_space.
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* The walk is limited to only the given page-size index range, but if
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* the index boundaries cross a huge page-table entry, that entry will be
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* included.
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*
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* Also see walk_page_range() for additional information.
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*
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* Locking:
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* This function can't require that the struct mm_struct::mmap_sem is held,
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* since @mapping may be mapped by multiple processes. Instead
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* @mapping->i_mmap_rwsem must be held. This might have implications in the
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* callbacks, and it's up tho the caller to ensure that the
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* struct mm_struct::mmap_sem is not needed.
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*
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* Also this means that a caller can't rely on the struct
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* vm_area_struct::vm_flags to be constant across a call,
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* except for immutable flags. Callers requiring this shouldn't use
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* this function.
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*
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* Return: 0 on success, negative error code on failure, positive number on
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* caller defined premature termination.
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*/
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int walk_page_mapping(struct address_space *mapping, pgoff_t first_index,
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pgoff_t nr, const struct mm_walk_ops *ops,
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void *private)
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{
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struct mm_walk walk = {
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.ops = ops,
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.private = private,
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};
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struct vm_area_struct *vma;
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pgoff_t vba, vea, cba, cea;
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unsigned long start_addr, end_addr;
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int err = 0;
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lockdep_assert_held(&mapping->i_mmap_rwsem);
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vma_interval_tree_foreach(vma, &mapping->i_mmap, first_index,
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first_index + nr - 1) {
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/* Clip to the vma */
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vba = vma->vm_pgoff;
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vea = vba + vma_pages(vma);
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cba = first_index;
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cba = max(cba, vba);
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cea = first_index + nr;
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cea = min(cea, vea);
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start_addr = ((cba - vba) << PAGE_SHIFT) + vma->vm_start;
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end_addr = ((cea - vba) << PAGE_SHIFT) + vma->vm_start;
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if (start_addr >= end_addr)
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continue;
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walk.vma = vma;
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walk.mm = vma->vm_mm;
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err = walk_page_test(vma->vm_start, vma->vm_end, &walk);
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if (err > 0) {
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err = 0;
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break;
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} else if (err < 0)
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break;
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err = __walk_page_range(start_addr, end_addr, &walk);
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if (err)
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break;
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}
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return err;
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}
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